In recent years drug formulations have been developed in dry powder form, e.g. for delivery by inhalation, or by admixing in a solution for delivery by intravenous infusion. Such dry powder formulations include existing compounds reformulated into dry powder form and newly developed compounds, used in the treatment of many conditions and diseases.
Drug formulations in the form of inhaled dry powders offer advantages over other forms such as liquids and tablets, particularly when considering storage and stability.
Oral or nasal delivery of a medicament using a dry powder medicament delivery device is a particularly attractive method of drug administration as such devices can be relatively easy for a patient to use. As well as delivering medicament to treat local diseases of the airway and other respiratory disorders, dry powder medicament delivery devices have more recently also be used to deliver drugs to the bloodstream via the lungs or nasal passages, thereby avoiding, for example, the need for injections.
One advantage of delivering a drug in a dry powder form is that very low dosages of the medicament may be used. However, in many situations the disadvantage of using dry powder formulations lies in the complication of actual delivery to the patient's area of treatment and/or the metering of very low dosages of medicament. The principle problem lies in the accurate metering and containment of a unit of dose and subsequent appropriately controlled release or dispensing of the unit dose. This is a significant impediment for the pharmaceutical industry in developing the potential of dry powder formulations to end products.
Dry powder delivery devices are most commonly known in the form of dry powder inhalers, these range from metered dose devices such as Clickhaler® where the dry powder medicament is stored in a reservoir and metered by operation of the device; to unit dose devices where the medicament is stored in individual unit doses in capsules (e.g. Spinhaler®) or foil blisters (e.g. Diskhaler®). These devices are generally cumbersome and complex in construction and, although suitable for their intended use for delivering medicament to the lung, their adaption for delivery to other areas of treatment, such as the nasal passage and/or nasal cavity, is generally unsatisfactory.
Furthermore, for delivery of a dry powder medicament by way of an intravenous infusion, the process of admixing a powdered drug to an infusion bag can involve the following steps:                Drawing a specified volume of the infusion fluid into a syringe.        With a needle on the syringe injecting the infusion solution into a rubber stoppered vial containing the weighed amount of powdered drug substance.        Mixing the infusion solution with the powdered substance        Drawing the powder mixture or solution of drug back into the syringe        Transferring the mixture/solution from the syringe into the large volume injection solution usually contained in a flexible plastic bag.        
However, there are a number of problems associated with this procedure;                The process can be cumbersome involving several steps        Needles are involved to facilitate injection into the vial containing drug        Storage may be an issue because the drug vial needs to have enough capacity to accommodate the fluid volume        Dosage errors may be created in the transferring process        Handling of chemotherapy drugs may be complicated by the transferring process.        
The present invention seeks to provide a dry powder medicament delivery device that overcomes or substantially alleviates the problems with conventional inhalation devices and/or infusion devices. In particular, the invention seeks to provide a device having a significantly simpler construction than known devices. The dry powder medicament delivery device of the present invention is also easier to manufacture, assemble and operate, as well as being cheaper to manufacture.
The present invention now described offers a means of metering a unit dose of dry powder into a container or cartridge that is readily adaptable to a range of devices designed to suit a diverse range of treatment types. One advantage is that of the delivery device of the present invention is that it is capable of accurately delivering a metered dose of a powdered medicament and is easy to operate, inexpensive and disposable.
A further advantage of the present invention is that the method of metering/filling the dry powder into the unit dose container or cartridge is capable of being easily scaled from laboratory hand filling to mass production.
Furthermore, recently dry powder intranasal vaccines have been developed. There are a number of advantages to intranasal delivery of drugs, in particular in dry power form. Intranasal drug delivery offers rapid uptake into the blood stream by absorption through the nasal mucus, the potential to reduce or eliminate cold chain management of vaccines during storage and transportation, and the elimination of needles and the potential for needle stick injuries.
Intranasal vaccination represents an attractive non-invasive alternative to needle-based injection and provides superior protection at mucosal surfaces. However, new formulations and delivery devices are needed to improve efficacy and reduce the refrigerated storage and distribution requirements associated with standard liquid vaccines.
Vaccines formulated as liquids can be subject to chemical degradation, e.g., aggregation, denaturation, hydrolysis, and oxidation that can result in their inactivation. Liquid vaccine formulations can also be sensitive to temperature: high temperatures can increase inactivation, and freezing temperatures can result in ice that can damage antigen in the vaccine. Thus, to prevent inactivation, liquid vaccines often must be stored at a temperature range of from 2-8° C.
The mode of administration of a vaccine can play a role in its efficacy. One mode of administration, non-parental administration (e.g., nasal), can induce and promote mucosal and systemic immune responses. In addition, nasal mucosa can help bind a virus or other pathogen at the mucosal surface, preventing access of the pathogen to deeper tissues and/or decreasing the likelihood of full-blown infection.
A yet further advantage of the delivery device of the present invention is the use of a novel medicament carrying cartridge. US Patent application No. 2007/060868 and U.S. Pat. No. 6,398,074 describe medicament delivery devices which, when actuated, deliver a medicament powder with a generally linear flow. Such devices will generally suffer from a lack of deagglomeration of the powder. This contrasts with the novel medicament carrying cartridge hereinafter described which provides a non-linear pathway for the powder, aiding, inter alia, deagglomeration.